This invention relates to an expandable sheath and more particularly to a dual valve, reinforced, large-diameter expandable sheath and method of use.
Expandable access catheter assemblies have heretofore been provided to facilitate the placement and removal of diagnostic and therapeutic catheters through the vascular system. Such catheter assemblies included a flexible variable-diameter catheter body, a diameter control stylet and a flexible Y-hub. The flexible Y-hub incorporates an adjustable hemostasis valve and a side port in one branch and a diameter control stylet guide wire in another branch. A flexible variable diameter catheter body is secured to the flexible Y-hub and can be expanded between a collapsed position and an expanded position by the stylet guide wire. Several deficiencies have been found in such a device. For example, the adjustable hemostasis valve is incapable of accepting large catheters. The flexible variable-diameter catheter body is objectionable in that it has a tendency to reduce in diameter and hold onto large-diameter catheters when it is attempted to place the same through the catheter body. In addition, the tip of the stylet guide wire catches a large-diameter catheter which causes elongation of the catheter body and reduction in its diameter to grab and prevent further advancement of the large-diameter catheter. Further, the tip of the stylet guidewire may, in certain circumstances, snag the variable-diameter catheter during removal. Additional problems with existing art involve the lack of safety features to protect against operator induced inadvertent advancement of a stylet guide wire distally into the vascular system beyond a desire distance. There is therefore a need for a new and improved large-diameter expandable sheath which will overcome these deficiencies.